Cassido's interview question of the week 5/19/19 - Find the last non-repeating character in a given string.

lastUnique.java

import java.util.HashMap;

/**
 * Created by kylel95 on 5/21/19.
 * Find the last non-repeating character in a given string.
 */
public class lastUnique {

    public static void main(String [] args){
        String s = "candy canes do taste yummy";
        String dups = "aabbcc";
        System.out.println(nonRepeat(s)); //u
        System.out.println(nonRepeat(dups)); //null

    }

    /**
     * Find the last non-repeating character in a given string.
     * @param s String to check
     * @return the last nonrepeating character in the string
     */
    public static String nonRepeat(String s){
        HashMap<Character, Integer> map = new HashMap<>();
        char last = ' '; //null
        for(char c: s.toCharArray()){
            if(!map.containsKey(c)){
                map.put(c, 1);
            }
            else{
                map.put(c, map.get(c) +1);
            }
        }
        for(char c: s.toCharArray()){ //get last nonrepeating character
            if(map.get(c) == 1){
                last = c;
            }
        }
        if(last == ' ') return null;
        return String.valueOf(last);
    }

}